What is Metabolism?
Metabolism is your body's method of converting calories, from the food you eat, into energy needed to power all the physiological processes that keep you alive and kicking 24/7. The minimum amount of energy your body needs to keep you going is called Base Metabolic Rate (BMR).
Calories in food—protein, fat and carbohydrates—fuel your BMR. Each of us requires a unique daily number of calories to maintain BMR so we can breathe, grow, think, sleep, digest food, and filter waste. Age and lifestyle are significant factors in calculating BMR. If you sit more than you move each day, your BMR is lower and your daily calorie needs are lower, too.
Losing or gaining weight is about energy balance (calories taken in - calories burned off). Take in more calories than your body needs for maintaining BMR (or take in more calories than you use for physical activity) and you will gain weight.
It's in My Genes!
Your genes (and hormones) play a role in metabolism because they can influence the potential you have to grow muscles (how dense and how big) and how your body stores fat. However, genetic and hormonal mechanisms in metabolism are extremely complex. There are no definitive theories. Yet, many people have lost and maintained a tremendous amount of weight despite their family history. Many health experts agree, “Your genes are not your fate.”
Chances are your 'slow metabolism' has more to do with your diet and the type of exercise you are (or are not) doing on a regular basis.
If your exercise routine builds lean muscle, that helps rev-up your metabolism. Muscle tissue requires more energy to maintain than fat tissue. This is why people with leaner bodies (a higher muscle to fat ratio) have a higher BMR. (Those are the folks who eat carrot cake that doesn't 'go right to their hips.')
Build a 24-Hour Fat Burning Body
The first key to revving-up metabolism is eating a whole foods diet: lean protein, high quality grains, plant-based fats and oils, fresh fruits and veggies, and drinking lots of water.
To really turn-up the heat on your metabolism, and your waistline, you'll want to try the muscle-building, never boring workouts listed below. These workouts help your body generate a 'post-exercise burn' that can rev up your metabolism for 2 – 24 hours after you finish a workout. Factors that determine the afterburn effect include your current fitness level and body composition, the intensity and duration of exercise, and type of exercise performed.
Just remember: Our bodies are designed to adapt; beginners to elite athletes both have to change-up their routine every few weeks to continue to see progress.
Circuit Training: Exercises all the major muscle groups in one workout (30-45 minutes) and may include body-weight movements, machines, dumbbells, and exercise bands. Exercises are performed for 8-12 reps, 1-3 sets of each.
High-Intensity Interval Training (HIIT). These workouts alternate bouts of maximal physical effort with a rest (or lower intensity) period for set times (e.g., 40 seconds max, 15 seconds lower effort). HIIT principles can be integrated into a variety of exercise routines including walk/run, swim, weight training, and group classes. Research shows an increase in calorie burn for up to 24-hours post exercise.
Metabolic Conditioning routines are highly intense and designed to engage different physiological "energy" pathways in the body. These workouts typically use a "suspension exercise system" (e.g., TRX) but can be integrated into other fitness activities. It's best to have a metabolic exercise routine designed and supervised by an experienced exercise specialist who can appropriately alter the intensity, reps, sets and rest intervals.
CrossFit often done as a group activity, this involves a variety of functional movements that engage the whole body at a relatively high intensity. The routines involve running, rowing, squatting and other exercises that support the way your body moves on a daily basis. The aim is to generate maximal power in as little time as possible to get stronger and fitter.
Calculate your BMR: http://www.bmi-calculator.net/bmr-calculator/
American College of Sports Medicine. http://www.acsm.org/search-results?q=metabolic%20training Accessed on March 10, 2016. – includes items listed below:
"Factors that Influence Daily Caloric Needs." (Bushman, B.) http://www.acsm.org/public-information/acsm-blog/factors-that-influence-daily-calorie-needs
"Metabolism is Modifiable with the Right Lifestyle Changes." (2011).
"High-Intensity Interval Training." (2014; brochure: Kravitz, L. ed.). https://www.acsm.org/docs/brochures/high-intensity-interval-training.pdf
NHS.com. "How Can I Speed Up My Metabolism?" (last reviewed Mar 2015). Accessed on March 10, 2016. http://www.nhs.uk/Livewell/loseweight/Pages/how-can-I-speed-up-my-metabolism.aspx
For a lay person's guide to metabolism myths and facts, please see:
Le, Trinh. "A Beginner's Guide to Your Metabolism." (last reviewed Feb 2016). Accessed on March 10, 2016. http://blog.myfitnesspal.com/a-beginners-guide-to-your-metabolism/?native_client=1
"Evidence based exercise - clinical benefits of high intensity interval training." Aust Fam Physician (2012) Dec; 41:12. 960-2. PMID: 23210120PMID: 23210120. http://www.ncbi.nlm.nih.gov/pubmed/23210120
Marcinko, Katarina et al. "High Intensity Interval Training Improves Liver and Adipose Tissue Insulin Sensitivity." Molecular Metabolism 4.12 (2015): 903–915. PMC. Web. 10 Mar. 2016. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4731736/
McCAll, Pete. "How to Get Real Results with Metabolic Conditioning." American Council on Exercise Blog (2012). https://www.acefitness.org/blog/2936/how-to-get-real-results-with-metabolic
Glassman, G. & Glassman, P. "Metabolic Conditioning Glossary." CrossFit Journal Articles. (2006). Accessed on March 10, 2016. http://library.crossfit.com/free/pdf/10_03_met_cond_glosry.pdf
CrossFit.com "What is Crossfit?" Accessed on March 10, 2016. https://www.crossfit.com/what-is-crossfit
Kravitz, L. "Metabolic Effects of HIIT" University of New Mexico. Accessed on March 10, 2016. https://www.unm.edu/~lkravitz/Article%20folder/metabolicEffectsHIIT.html
Interview with Dr. Dean Ornish. Personal Communication, 2009-2010.